X-ray Emission Line Profiles from Wind Clump Bow Shocks in Massive Stars

Abstract

The consequences of structured flows continue to be a pressing topic in relating spectral data to physical processes occurring in massive star winds. In a preceding paper, our group reported on hydrodynamic simulations of hypersonic flow past a rigid spherical clump to explore the structure of bow shocks that can form around wind clumps. Here we report on profiles of emission lines that arise from such bow shock morphologies. To compute emission line profiles, we adopt a two component flow structure of wind and clumps using two "beta" velocity laws. While individual bow shocks tend to generate double horned emission line profiles, a group of bow shocks can lead to line profiles with a range of shapes with blueshifted peak emission that depends on the degree of X-ray photoabsorption by the interclump wind medium, the number of clump structures in the flow, and the radial distribution of the clumps. Using the two beta law prescription, the theoretical emission measure and temperature distribution throughout the wind can be derived. The emission measure tends to be power law, and the temperature distribution broad in terms of wind velocity. Although restricted to the case of adiabatic cooling, our models highlight the influence of bow shock effects for hot plasma temperature and emission measure distributions in stellar winds and their impact on X-ray line profile shapes. Previous models have focused on geometrical considerations of the clumps and their distribution in the wind. Our results represent the first time that the temperature distribution of wind clump structures are explicitly and self-consistently accounted in modeling X-ray line profile shapes for massive stars.

To appear in Astrophysical Journal

References in corpus (13)

• X-Ray Spectroscopy of Stars
• Neglecting the porosity of hot-star winds can lead to underestimating mass-loss rates
• The Effect of Porosity on X-ray Emission Line Profiles from Hot-Star Winds
• High resolution X-ray spectroscopy of bright O type stars
• Global X-ray properties of the O and B stars in Carina
• An Extensive Collection of Stellar Wind X-ray Source Region Emission Line Parameters,Temperatures, Velocities, and Their Radial Distributions as Obtained from Chandra Observations of 17 OB Stars
• Direct spectroscopic observations of clumping in O-star winds
• Signature of wide-spread clumping in B supergiant winds
• A new paradigm for the X-ray emission of O stars from XMM-Newton observations of the O9.7 supergiant zeta Orionis
• Evidence for the importance of resonance scattering in X-ray emission line profiles of the O star $\zeta$ Puppis
• The Effects of Clumps in Explaining X-ray Emission Lines from Hot Stars
• The Correlation between X-Ray Line Ionization and Optical Spectral Types of the OB Stars
• Highly Accelerated Diamagnetic Plasmoids: A New X-ray Production Mechanism for OB Stellar Winds

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